Antarctica is the last continent to be explored and exploited, and thus the least documented continent in terms of its biodiversity. It has many unusual and interesting features ranging from the marine life to the icy landscapes. This continent lies entirely within the Antarctic circle and is located around the South Pole in latitudes to the south of 66 Degrees and 33 Minutes South. It is covered by around 90% of the world’s ice, which has an average thickness of nearly 2,000 meters. Only high mountain peaks and coastal rock outcrops are without permanent ice or snow, constituting only around 5% compared to the rest of the ice sheet.
Marine Habitats of Antarctica
The Antarctic ocean and the seas that surround the continent provide a unique environment that hosts unique fish species and other forms of marine life. The Antarctic convergence, which is basically the convergence of the three main oceans namely the Pacific, Indian, and Atlantic oceans, forms a barrier to the shallow living fish allowing them to thrive in this unique condition. The fish are found very deep in the sea water where the temperatures are more favorable than on the sea surface which is at freezing point.
The Antarctic Toothfish, Dissostichus mawsoni, is native to the Southern Ocean and is a species of cod fish. It has biserial dentition which gives it an appearance similar to a shark, and serves as the source of the name ‘toothfish’. A fully grown toothfish can measure more than 1.7 meters and weigh around 135 kilograms. It is the largest Antarctic fish and plays a significant ecological role to that of sharks found in oceans. It is a voracious predator and can feed on its own offspring. It is characterized by a broad head, long anal and dorsal fins, elongated body a caudal fin that is akin to a rudder.
The Emerald Rockcod, Trematomus bernacchii, is found along the sea floors and is well adapted to low and stable temperatures. It has a brown color with dark spots. The female species can reach a length of 35 centimeters while males grow to a maximum of 28 centimeters. The Emerald rockcod is a cod icefish that feeds on gastropods, amphiphods, isopods, and certain algae. It is caught for commercial purposes.
The Antarctic Silverfish, Pleuragramma antarcticum, is regarded as the only true pelagic fish living in Antarctic waters. It is widely distributed in the Southern Ocean and especially in the Antarctic Peninsula, Shetland, Weddell, South Orkney islands, Ross sea and Davies sea. The maximum reported age is 20 years for the Antarctic silverfish. Mature fish have a maximum length of 25 centimeters, though the common length is 15 centimeters. Female species spawn for the first time between the age of 7 to 9 years. They feed on eggs, copepods, polychaetes, and chaetognaths.
The Antarctic dragonfishes consist of around 15 different species, notably including Bathydraco antarcticus, Gerlachea australis, Acanthodraco dewitti, Akarotaxis nudiceps, and Prionodraco evansii. They are found in deep sea waters and native to the Southern Ocean. These species grow up to a varied length of between 2 centimeters and 50 centimeters, and reach maturity after 3 to 4 years. They breed from July until December. They feed on tiny vertebrates and invertebrates. Currently, certain species such as the Gymnodraco acuticeps are under threat from the increasing levels of carbon dioxide and increase in ocean water temperature in the Antarctica.
Other Fish Species Found in Antarctic Waters
Other fish species native to Antarctica include the Bald Notothen, the Ploughfish, Mawson's Dragonfish, the Ross Sea Cod Icefish and the Ocellated Icefish.